This has been bugging me for a long time so I need to ask the question.
What is the difference between / and ./, is it just down to server settings?
For example, if we were looking for an images folder in the root directory we would write:
<img src="/images">
However, another server will only accept it as follows:
<img src="./images">
It's not a biggie, but in an ideal world I'd like to think I could transfer my sites to another server relatively easily without having to update minor details like these.
Of course, I can declare it in PHP and set it once in a config file, but it really is bugging me. Why is there two methods for declaring the root?
To reference files relative to the current page, you can either write the path plainly without a prefix, or you can be explicit about it by prefixing with ./. To reach files with paths relative to the root of your site, you prefix the path with /.
Summary
/ absolute path (full path to resource from root directory)./ relative path from current directory (equal to not specifying any folder prefix)../ relative path from parent directory../../ relative path from parent of parent
Examples
Current URL Resource path Resolves to
/pages/home.html ./picture.jpg /pages/picture.jpg
/pages/home.html ../img/picture.jpg /img/picture.jpg
/pages/about/home.html /img/picture.jpg /img/picture.jpg
/pages/about/home.html img/picture.jpg /pages/about/img/picture.jpg
/home.html img/picture.jpg /img/picture.jpg
This is the same only if the source page (the one containing this HTML) is itself at the root of the domain.
In the general case, ./images is equivalent to images.
This has nothing to do with HTML, apart from the fact that URLs are used in HTML, too. This is defined in URL specifications. Briefly, ./ is relative to current base URL, and / is relative to the server root (technically, it refers to the server part of the base URL).
来源：https://stackoverflow.com/questions/15357693/differences-in-declaring-your-root-directory-in-html